Sodium and potassium alkoxides have been known for about 100 years and have been used commercially for various purposes for more than 50 years. However, no truly satisfactory way of manufacturing these substances cheaply, efficiently and with low energy costs have been found.
One of the oldest and simplest methods known in the art for the manufacture of these alkoxides is the reaction of an anhydrous alcohol with the respective metal, sodium or potassium. This reaction, however, involves the danger and inconvenience of using a highly reactive metal and the need for subsequent handling of the evolved hydrogen gas.
U.S. Pat. No. 1,712,830 suggests the reaction of sodium hydroxide with an anhydrous alcohol of at least 2 carbon atoms with azeotropic removal of the formed water by means of an inert solvent. Not only is azeotropic removal of water difficult, expensive and time consuming, but it cannot be done when the alcohol is methyl alcohol.
U.S. Pat. No. 2,278,550 involves the reaction of an alkali metal salt of a weak acid with an alcohol, e.g. anhydrous sodium sulfide and methanol to form sodium methoxide and sodium hydrogen sulfide. As is apparent, the subsequent handling of the toxic and foul smelling hydrogen sulfide presents considerable problems.
U.S. Pat. Nos. 2,796,443 and 2,877,274 involve the reaction of sodium hydroxide with alcohols using various column and distillation techniques. However, the engineering is difficult and complex and there is poor control over the process.
U.S. Pat. No. 2,437,272 describes the use of alkali metal amalgams in continuous flow processes. However the problem of this process is similar to the uses of alkali metals alone plus the additional problem of the toxic properties of the mercury contained in the amalgams.
U.S. Pat. No. 3,094,546 relates to the use of calcium carbide. However the byproduct is acetylene which of course requires special handling. In addition, calcium carbide is expensive and requires considerable energy in its production.
Bulgatsch, et al. in Chemisches Zentralblatt, Volume I (1939) page 642 describes the reaction of sodium hydroxide with calcium oxide at a temperature of 100.degree.-130.degree. C. and at a pressure of 4-5 atmospheres. Reaction at such high pressures and temperatures is difficult and expensive.